Welding apparatus



May 29, 1956 E. LAPORTE 2,748,237

WELDING APPARATUS Filed June 28, 1954 179/60/0/1' Zdmmz/ Japan? UnitedThe present invention pertains to a novel apparatus for arc welding.

The principal object of the invention is to provide a substantiallyconstant voltage in welding instead of a constant amperage, therebyincreasing the efiiciency of the welding operation and improving theeffectiveness of the weld.

It is well known that the actual procedures of arc welding are notalways satisfactory. Since the quality of the weld is a function of thevoltage, the invention provides a means for handling all the powerrequired by the arc for fusing the metal. This power is a function ofEl=voltage current.

Another object is to control the adjustment of the energy necessary forthe arc without the use of fuses.

A further object is to provide an accumulator or battery which permits aconstant arc effect, that is, stable operation with power of a half, afourth, etc., of the maximum required without accumulation.

A still further object is to enable variations of voltage on thetransformer as a function of that desired on the accumulator the latterbeing a function of the desired eifect at the arc.

In the accomplishment of these objects, the invention comprises the useof an accumulator to obtain a constant voltage of a given weld.

The secondary of a transformer is included in a closed circuit thatcontains a single-phase full wave rectifier of the undulating type, amercury diode with two anodes, or other suitable form. This circuit isjoined to a controller, that is, a solenoid adapted to open a switch inthe event of a direct short circuit, the switch being connected to themetal being worked upon. Another conductor extends from the midpoint ofthe secondary to the welding electrode. Finally, an accumulator orbattery is branched between the last named conductor and the input sideof the switch and is adjustable from the conductor. A fuse ordirectional relay is mounted between the rectifiers and accumulator. Aresistance is used to control the overcurrent relay.

The invention is fully disclosed by way of example in the followingdescription and in the accompanying drawings in which:

The single figure is a diagram of the circuit.

As clearly indicated, the invention comprises a transformer 1 having itsprimary winding connected to a source of power and the ends of thesecondary winding joined in a closed circuit by a conductor 2 having ajunction point 3. Rectifier 4 is mounted in the conductor 2 and may beof the full wave type, mercury diode with two anodes, or other suitableform.

A conductor 5 extends from point 3 to a switch 6 and thence to the baseor metal '7 on which the welding is performed. A solenoid 8 connected inparallel with the switch 6 by a conductor 9 actuates an armature 10connected to the switch to open the switch when the output is too high.

Patent 0 ice A welding cement coated electrode 11 is connected by aconductor 12 to the midpoint of the secondary winding. The cementcoating is used for the protection of the arc and the metal. To theconductor 12 is also connected a movable accumulator 14 which has oneend connected to the conductor 5.

A resistance 15 is mounted between the switch 6 and the base '7 and isadjustably engaged by an end of the solenoid conductor 9, in order tovary the current flowing through the solenoid 8. A fuse or directionalrelay 16 is mounted in the conductor 5 between the point 3 and thebattery 14.

The described circuit permits a relatively constant voltage, that is, avariation of four to five volts with twentyfive volts at the are. Aconstant voltage results in a uniform weld of good quality. The requiredvoltage is a function of the size of the electrode and the desired sizeof are. It may be noted that existing apparatus are the cause of largevariations and irregularities at the expense of power consumption. Asanother advantage of the invention, when the voltage at the arc isincreased a cutting arc may be produced.

Although a specific embodiment of the invention has been illustrated anddescribed, it will be understood that various alterations in the detailsof construction may be made without departing from the scope of theinvention as indicated by the appended claims.

What I claim is:

1. A welding apparatus comprising a transformer, a conductor joining theends of the secondary winding thereof, rectifying means in saidconductor, a metal working base, a second conductor extending from thefirst conductor to said base, a welding cement coated electrode at saidbase, a third conductor extending from the midpoint of the secondarywinding to said electrode, an accumulator between the second and thirdconductor, and an automatic switch in the second conductor between saidaccumulator and said base.

2. A welding apparatus comprising a transformer, a conductor joining theends of the secondary winding thereof, rectifying means in saidconductor, a metal working base, a second conductor extending from thefirst conductor to said base, a welding cement coated electrode at saidbase, a third conductor extending from the midpoint of the secondarywinding to said electrode, an accumulator between the second and thirdconductor, a contact from said third conductor and adjustable on saidaccumulator, and an automatic switch in the second conductor betweensaid accumulator and said base.

3. A Welding apparatus comprising a transformer, a conductor joining theends of the secondary winding thereof, rectifying means in saidconductor, a metal Working base, a second conductor extending from thefirst conductor to said base, a welding cement coated electrode at saidbase, a third conductor extending from the midpoint of the secondarywinding to said electrode, an accumulator between the second and thirdconductor, a switch in the second conductor between said accumulator andsaid base, and a solenoid connected across said switch and having anarmature conncted to said switch.

4. A Welding apparatus comprising a transformer, a conductor joining theends of the secondary winding thereof, rectifying means in saidconductor, a metal working base, a second conductor extending from thefirst condoctor to said base, a welding cement coated electrode at saidbase, a third conductor extending from the midpoint of the secondarywinding to said electrode, an accumulator between the second and thirdconductor, a contact from said third conductor and adjustable on saidaccumulator, a switch in the second conductor between said accumulatorand said base, and a solenoid connected across said switch and having anarmature connected to said switch.

5. A welding apparatus comprising a transformer, a conductor joining theends of the secondary winding thereof, rectifying means in saidconductor, a metal working base, a second conductor extending from thefirst conductor to said base, a welding cement coated electrode at saidbase, a third conductor extending from the midpoint of the secondarywinding to said electrode, an accumulator between the second and thirdconductor, a switch in the second conductor between said accumulator andsaid base, and a solenoid connected across said switch and having anarmature connected to said switch, and means for adjusting the currentin said solenoid.

6. A welding apparatus comprising a transformer, a

conductor joining the ends of the secondary winding thereof, rectifyingmeans in said conductor, a metal working base, a second conductorextending from the first conductor to said base, a welding cement coatedelectrode at said base, a third conductor extending from the midpoint ofthe secondary winding to said electrode, an accumulator between thesecond and third conductor, a switch in the second conductor betweensaid accumulator and said base, and a solenoid connected across saidswitch and having an armature connected to said switch, a resistance inthe second conductor between switch and said base, one end of saidsolenoid being adjustably connected to said resistance.

No references cited.

